A number of leveling tools have been developed for determining an object's angular position relative to a substantially vertical and/or horizontal axis. For example, “bubble” or “spirit” levels have been used by carpenters for many years. More recent developments in this field have led to electronic light-indicating levels for indicating an object's angular position relative to a substantially vertical and/or horizontal axis. For example, some conventional “illuminated levels” include mercury switches configured to complete linear circuits including light emitting diodes and/or audio speakers such that the illuminated level emits a light and/or sound when the level is positioned either parallel to a vertical axis or parallel to a horizontal axis (indicating a level condition).
However, conventional illuminated or electronic levels are designed to be used as tools for use only during carpentry projects and/or other household projects (such as the hanging of framed artwork). Furthermore, such conventional illuminated or electronic leveling tools include many features (including, for example, multi-color LED lighting) for indicating a level condition by illuminating a first color LED and a number of different angular orientations using LED's of various colors that sequentially illuminate as the leveling tool is oriented in an off-level condition. The various features and settings present in such conventional tool-based leveling devices necessitates that such devices be relatively large and obtrusive. Furthermore, such conventional leveling devices are configured to emit a perceptible signal (such as the illumination of a red LED light) when the device is oriented in a level condition.
While some simple leveling devices have been integrated with picture-hanging hardware for indicating an off-level condition in a wall hanging, such conventional integrated levels utilize a “spirit level” configuration that must be viewed closely by a user to determine if the wall hanging is oriented at a selected acute angle relative to dead level.
Thus, there exists a need in the art for an electronic level device that is adapted to be unobtrusively integrated with a hanging picture frame or other wall hanging so as to provide a user with an easily-perceptible signal only when the wall hanging is “off level” or oriented at a selected acute angle relative to a substantially horizontal axis. There further exists a need in the art for an electronic level device that does not emit a perceptible signal when oriented in a substantially level position such that the device goes unnoticed until it detects a substantially “off-level” orientation.